In a world where small, plant-born creatures called Fairia are cultivated as popular pets, a technology developed by his own parents has left Nao Saionji bitter and withdrawn. Years ago, his mother deceived him into handing over his pet Fairia, Lupi, for a checkup—only to use the creature in an experiment that killed it. Swearing never to keep a Fairia again, Nao grows distant from his family and his environment.

One day, Nao picks up a discarded clematis flower and brings it home. From it emerges a tiny, innocent girl whom he names Claire. Unlike ordinary Fairia, Claire is a legendary Fairial—a being that can freely change her size from pea‑sized to roughly human form. She is pure, affectionate, and inexplicably drawn to Nao, slowly chipping away at the walls he built after Lupi’s death. However, Nao’s father, a leading researcher, sees Claire as a scientific prize and wants her isolated in the research facility alongside Cattleya, the only other known Fairial. Nao must protect Claire while uncovering the secrets behind Fairials and the Fairia seeds.

The story follows Nao, Claire, and a small circle of friends: the eccentric fairy enthusiast Jun Yanagisawa, who designs clothes and furniture for Claire; Mami Kuwahara, a gentle caretaker who raised a talking Fairia; and the Anderson siblings, whose own complicated history with Fairia forces Nao to confront what it means to care for another being. Through slice‑of‑life moments and escalating tension with the research institute, Nao gradually reopens his heart, learning that trust and connection are worth the risk, even when the past left deep scars.